In, for example, clean rooms in semiconductor manufacturing factories, the quantity of particles suspended in the air within the room is monitored using a particle detecting device. In evaluating the particle capturing performance of particle detecting devices, the correspondence between the quantity of particles actually dispersed in the air within the test environment and the results of detection by the particle detecting device is examined. (See, for example, Japanese Unexamined Patent Application Publication 2004-159508, Japanese Unexamined Patent Application Publication 2008-22764, Japanese Unexamined Patent Application Publication 2008-22765, and Japanese Unexamined Patent Application Publication 2005-77251.)